Possible Clues:

• Red traffic sign
• 'Stay out' sign
• Road warning
• "Keep out!" sign ... or, in three parts, each answer to a starred clue
• 'Keep out!' sign ... or, in three parts, each answer to a starred clue
• Restricted access sign
• TMO's ruling nut has punched and passage denied
• Unsuccessful competitor's situation, perhaps way to go ahead is barred